thurston



May 5, 1925. v

F. w. THURSTON DRILL n l iles; April 18. 1922 2 Sheets-Sheet 1 1 IN VENT'OR f 3% a, m B w P x f! 1M4 N/MW Z I May 5, 1925. 1 Re. 16,061

Y F. w. THURSTQN k DRILL Original Fi p i 18, 1922, 2 sheets-sheet 2 A TTORNEY Reiss ued May 5,1925.

uNirspfs'TA FRED W. THURSTON; OF NEW YORK, NJY.

DRILL.

Original No. 1,477,855, dated T 0 all wk am) it may concern Be it known that I, FRED WITHUBs'roN, a citizen of the United States, residing at New York, in the county of New York and State of New York, have invented .certain new and useful Improvements in Drills, of which the following is 'a full, clear, andexact description, such as;wi1l enable others skilled in the art to which it appertains to make and usethe same. 4

This invention relates to "drills which are adapted for drilling rock and thelike; and more particularly to drills designed to be percnssively driven, and adapted forldeep drilling'operations.

This invention has .for itsgeneral object an improved construction and arrangement of parts which is articularly durable and ellicient, and is 'rea ily adapted to manufacturing and drilling operations. I

A more specific object is to provide an improved drill havin parts individually adapted to withstanding the stresses and resisting the strains incident to their role in t-he'drilling operation.

g lnother object is'to provide a drill com prising separable. parts, each designed and selected to have properties intrinsically adapted to its particular duty in the drilling operation.

= Another object is to provide a drilling construction which 'is adapted to admit of the use of a variety of alloy-steels, each selected with especial reference to its particular function or location in the construction as a whole.

Another'object is ,to provide a drill construction which has separate sections fitted together each formed of a different alloy steel tempered and treated 'tb impart to it properties specifically adapted to its particular service in the drilling operation. Another object is to provide a construction for drillscomposed of separableparts which are rigidly articulated, possess ruggedness and wear-resisting qualities, and are designed to be readily assembled and disassembled; special provision being "made against thebinding or locking together ofv the parts.

Still another 0111661: is to\pr0vide a drill having a detachable-bit or head with an inother.

Ilecember 18, 1923, Serial No..554,858, filed April 18, 1922. Application for reissue filed March 30, 1925. Serial No. 19,536.

termediate shock-absorbing part which 'is adapted bit.

Other objects of this inventionwill in part be hereinafter specifically pointed out and in part obvious from the arrangements and constructions here set forth.

The 1nvent1on accordingly consists in the .features of construction, combinations of elements and arrangement of parts which will be exemplified in the construction liererigidly to support the detachable inafter set forth, and the scope of their apvplication will appear "in the appended claims' For a more complete understanding of the nature and advantages of this invention refshould be had tothe following deerence tailed description, which describes the-best illustrative embodimentsof this invention at present known to me, takenin-connection with the accompanying drawing in which: Fig. 1 shows, in perspective, an assembled drill embodying this invention;

Fig. 2 shows, in longitudinal section, the

shown. in Fig. 1-.

Fig. 2 shows, in longitudinal section parts in disassembled relation of thedrill of the separable parts contact with 7 each Figs. 6 and 7 show in perspective other forms of bitsadapted for use in. the imitudinal section illustrating proved drill construction of this invention;

and I t Fig. 8 shows a detail of the thread formations which are practically adapted to prevent locking or binding of the parts together. I

Referring now to the drawing, and particularly to Figs. 1 and 2, 10-denot'es the bitor drillhead which is separable from but rigidly supported by the drill-rod 11. The drill-rod, as illustrated in Figures 1' and 2, is not directly connected with the bit 10, but has'an intermediate or coupling -part or member 12, which in the instance shown is separable from the drill-rod proper. Q I

- being rotated during the drilling operation,

r cated form 10 and the drill-rod 11. The direction of the thread .is such that, when the drill is the drill and intermediate. part tend more tightly to screw together. In order that the shanks on which the threads 14and 15 are made shall be particularly resistant to fracture they are not threaded clear up to the shoulders at 16 on the bit, and at 17 on the drill-rod. The shoulder 17 on the drill-rod 11 is preferably'slightly upset, as

indicated at'17, inorder that theshoulder may be of the same diameter as that of the illgtermediate member 12 where these parts a ut. i

Inorder that the threaded engagement of the parts'shall not readily'bind or lock together, the engaging surface of the threads is diminished below that normally obtained for that of the given pitch by giving the threads a truncated formation such form of thread being sometimes referred to as the Franklin Institute type, and is shown in enlarged section .in Figure 8. Here the apexes of the threads are cut away as indicated at 18, the gutters between the threads being correspondingly filled-in, as indicated at 19. As a consequence, the strength to be had from the thread of given pitch is preserved, but the amount of en'- gaging surface is diminished so that eventhough the parts should be tightly engaged after a drilling operation, still only .a relatively small effort is required to unscrew them. It will be understood however that other forms of threads adapted to discharge this function of being readily unscrewed ma ere disclosed.

Shanks 14 and 15 may have little fillets, as shown at 20 and 21 where they meetthe shoulders 16 and 17 which strengthen them and prevent them from being readily fractured at this point. The ends of the member 12 are reamed out as shown at 22 and- 23 to provide a smooth, cylindrical surface fitting over the unthreaded portions of the shanks 14 and 15. the inturned edges being rounded off, as sliown at 24, sufficiently to fit into the curved fillets at 20 and 21. central passage, as indicated at 25, extends longitudinally through the drill-rod and a similar passage is provided, as indicated at 26 in the bit 10. When the bit and drillrod are in assembled relation, there is pro-- be used instead of the trun-' vided a continuous passage through whicha fluid medium, such as water or compressed air, may be fed during the drilling; operation to cool the' bit and assist in "the removal of chips and other particles of rock and'the like, resulting fromthe drilling operation. a

The bit 10 may have any desired form, a. cruciform bit beingshown in Figs. 1 and 2. As such the bit has four cutting edges 30 which'meet at right angles at the center of the face of the bit. .These edges are formed by eight converging plane surfaces on the bit which meet forming dihedral angles, In the bit illustrated the dimension from tip 31 to tip 31 along the cutting edges has the greatest transverse magnitude from which the stock of the bit gradually tapers backward until reduced to that of the base at the shoulder 16, as indicated are provided longitudinally of the ,bit disposed midway between the tips 31 and 31'.

Another form of bit having but one cutting edge is shown in Fig. 6. This bit is frequently referred-to as a Carr type of bit. In this bit the dimension from tip 41 to tip 41 is the maximum transverse dimension from which the stock of the bit tapers down to the stock of. the shoulder provided with shank 42 in order to provide clearance for the advance of the bit.

The sides of the tapering stock of the bit, in a. direction at right angles to the direction of the cutting edge, is'cut away, to provide clearance surfaces 43 past which the prod ucts of the drilling operation may be easily I,

washed by the stream of fluid entering/by way of-the central passage. This form also has a threaded shank 44 adapted toscrew into the threaded portion'of an intermediate member.

In Figure 7'is still another modified form of bit which has six cutting edges and is often referred to as 'a rose type'oof' bit. This bit also tapers back from the tip of the 'cutting edges 51 and 51 to the mai shank' 52 to provide proper clearance an also has fluted portions 53 disposed between the cutting tips, and has a threaded shank 54 for securing it into'the threaded portion of the intermediate member which is' to support it. x

By making; the drill in parts'it is possible to take full adva tage of the properties of the various alloy s eels known to the arts in devising the'drill construction when practicing this invention. Each part is specifically adapted to resist the strains attendant 'to its particular position in the drill construction, and incident to its role in the drilling operation. The bit is particu- Q vanadium steel, so shaped and tempered as ably made of a vanadium mild. steel and should outlast,

' cial stock designed for tool purposes;

to provide a cutting edge of suitable hardness which is adapted for repeated resharpenings and regrindings; which operations it is generally desirable to do at'the place where the drilling is being done. The bit as a whole is formedso as to avoid brittleness such as might be encountered in the ordinarily tempered tool steel, and the bit may havewear-resisting properties greater than tool steel. The shank 14 at the base of the main body of the bit in particular.-

is made to outlast the cutting edge; in gen eral the different parts of the bit have different properties.

The drill-rod 11 is made of a material which has fatigue resisting properties and hence may be styled as the anti-fatigue part of the drill. This drill-rod is prefersteel which may not be adapted to take a cutting edge but which has long-enduring qualities and antifatigue properties greater thar those of v in point of time, the service of: any other part of the drill. Thedrill-rod, as shown in Figs. 1 and 2, may be made from ordinary commersuch stock in the formation of this portion of the drill being threaded at the end designed to support the bit and in some cases upset and shouldered. ily be performed by or other mechanic,

an ordinary blacksmith and can be done at the mine or place where the drilling operation takes place. As a result the drill-rod, when broken, adapted readily to be repaired for further service.

The intermediate or coupling member 12 is fitted on the drill-rod 1.1 and serves as a chuck to support the bit on the drill-rod, and is especially designed-to have a shockabsorbing and, in certain constructions of the invention, a more pronounced cushioning function during .a drilling operation.

'It is preferably made of a chrome-nickel steel, such as is standard for the construction of certain types of tools well known in the arts. This steel is treated and tem-.

pered so that it will be tough and not readii crystallized or likely to chip as its func tion is largely to damp out the compressional vibration received from the reactive thrust of the driving force reflected, from the bit. g

The properties pointed out above, which it is desirable for the several parts to posscss in accordance with this invention, are not those incidentally possessed by prior drills, but are made to be the dominant properties which characterize these parts to the substantial exclusion of all others.

for the various drill parts in this invention ties are particularly outstanding. These This operation can read-.

are preferably equally spaced about the cirvention; as tor example, the bit 10 isre quired to be Wear-resisting to the rock material which is to be drilled. When drilling granite, the cutting edge must be harder than when drilling slate rock, yet wear-resisting to both. The alloy steels here described as suitable are not chosen becauseof their hardness, but because they are susceptible of being tempered to a state where the desired properalloy steels possess another property which obviously must be Considered when designing drills to embody this invention, namely a sufiiciently high elastic limit not to be-' come deformed in the service towhich they are put.

The intermediatemember when'in place may fit snugly against the shoulders 16 and 17 thus receiving and transmitting the compres'sional vibration from the bit chiefly to the surface of the drill-rod, avoiding thereby transmitting them directly to the threads, and I may also accomplish this object in the only other known manner, as a substitute for said shoulders, by making the inner ends of the bit and drill rod to abut within the intermediate part, in which case shocks and strains are still absorbed by the intermediate part. This intermediate member is. generally cylindrical in shape, but is preferably provided'with bowed ridges 66 along geo-' metrical elements of its cylindrical surface. These bowed ridges '66 are thus parallel, and

cumference of the member so as to provide channels 67 therebetween. This construction enables the ridges to perform a three-fold function; one of strengthening the'intermediate member, another of reaming out the hole bored as the drill advances, and a third of providing a passage for the -.chips and other material which is to be washed away by the fluid entering through the central passage of the drill as it advances in the drilling operation. The toughness of this member is preferably of an order such that it will outwear the period of service of many bits, and it may have shock absorbing properties greater than wrought iron.

Fig. 3 illustrates a modified form of drill in which the intermediate member -72 is formed integral with the drill rod 71 and receives a bit 70- in its threaded bore 73. This intermediate member 72 is formedon the upset'end of the drill-rod 71'which has the central passage 7 5 through which flows the medium for washing away the chips, etc., resulting from the drilling operation. This intermediate member as before preferably has the general cylindrical contour shown in Figs. 1 and 2 and is likewise preferably provided with bowed ribs 76 disposed longitudinally about its'eylindrical surface in order to strengthen it and ena'ltde it to ream'the hole being drilled. The threads on ,the pilot or shank 74 of the bit 70 preferably have the truncated form indi cated in Fig. 8, so that the bit can be readily unscrewed from the drill-rod when desired. Likewise the parts for a drill of this construction will be made of alloy steels, or other materials selected to provide properties specifically adapted to resist strains incident to their role in the drilling operation.

Fig. 4 shows still another modification in which the intermediate part 82 is made in-v tegral with the bit 80, and isadapted for screw threaded engagement on the shank 83 of the drill-rod 81. Thedrill-rod 81 is provided with i a longitudinal passage 85 through which fluid is fed to the bit through its longitudinal passage 86. Also the threads preferably have the truncated formation indicated in Fig. 8 so that the parts may be readily unscrewed, the shank 83 being provdied with a fillet Set to strengthen it at its juncture with the body of the drill rod proper, the bore of the intermediate part havingan unthreaded portion to fit over the unthreaded portion of the shank, 83 anda rounded off edge 8a adapted to fit intothe fillet at 84.

The body portion of the bit SO'preferably has a cylindrical contour in order to merge in the general cylindrical form of the intermediate meinber 82, which thereby provides suflicient stock adapting it to repeated resharpenings and regrindings although the materials transverse dimension from the tip 87 to tip becomes thereby reduced as the ori nal stock is groundaway from the face of the bit. The intermediate member in this form is also preferably provided with a bowed ridge 88 to strengthen it and {enable it to perform a reaming function during the drilling operation. In this modified form of drill, the parts here again will be made of selected to have properties specially adapted to resist the strains incident to their partieu'largoles' in the drilling operation.

'In Figure 5 ,still another modification is illustrated. Here the bit 90, instead of being provided with a threaded shank adapted to engage with a threaded bore on the interengage with a threaded bore formed in the upset portion of the drill-rod 91. These bores and shanks are formed with truncated threads and fillets as previously indicated in order that the parts may be readily separable after a drilling operation. The bit 90 has a longitudinal passage 97 which communicates with the passage 98 in the drillrod 91 through a passage 99 formed in the intermediate member 92. Here the separable nature of the parts of the drill affords the utilization of materials selected inclividually to resist the strains incident to their role in the drilling operation.

In operation, adrill of this invention is particularly adapted to be driven by a modern percussion type of rotating head or driving tool and willaccommodate the escape of air actuating the tool, by way of the, central passages as 25 and 26 formed therein; fluid may also be adapted'to remove the chips and other particles produced bythe drill as .it advances. The compressional vibration transmitted from the bit to the rest of the" drill, as a reaction from the driving thrust, is substantially a wavelike disturbance which compounds to some extent with the driving impulse, thereby producing regions where the vibrations are particularly severe, .thereby causing strains in the parts, and resulting generally in the development of fractures in drills prior to thisinvention. The use of an indeterminate member constructed in accordance with this invention, however, sufliciently absorbs the shocks of the compressional vibrations transmitted up through the drill so that the regions of strainare not sufliciently pronounced to develop fractures of a character which shortens life and service of the drill. But the compressional vibrations and shocks are not the only ones to which-the intermediate or coupling member is subjected. It is also subject to severeshocks of a tensional nature in the rapid and abrupt reversals of move men of the drill, and totorsional and shear-' \ingshocksdue to the rotational movement of the drill in the rock, and to bending and shearing shocks due to the whipping of the intermediate part of the drill out of the right axial line, which may occur in operation, and produces tensional impulses and shocks at one side of the intermediate member towards which the drill is bent sidewiseand compressional impulses and shocks at this time in the opposite side of the same member. It will be understood that all of the above mentioned rapidly periodic and wavelike stresses and shocks may be inflicted on said intermediate member at or about construction of the drill.

' limiting sense.

them by the material of said intermediate member; and my invention is independent of the separation and of the contact ofthe threaded ends ofthe coupled parts in the In consequence the periods of service of drills employing an intermediate or shock-absorbing member, in accordance with this invention, are relatively longer, thereby enabling drill ing operations to be effected with much greater average speed than heretofore. Also the special properties of the drill parts permit the drill to be driven actually at higher rates of speed than previous drills with consequent further economies iii the costs of drilling operations. After a .drilling operation, the type of thread .here used enables pair. I

As many changes could be made 111 the above construction and many apparently widely different embodiments of this invention could be made without departingfrom the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a I It is also to be understood that the language used in the following claims is intended to cover all of the generic and specific features of the invention hereindescribed, and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween. I use the word intermediate in describing the part 12, not necessarily in the sense of interposed, but in' the broader sense that it isthe intermediary connecting element in thedrill construction. D

Having described my invention, what I Patent is:

1. A drill adapted to be percussively driven into rock and the like, comprising a separable --bit' and drill rod, including an intermediate member; said bit'being formed and tempered to have wear-resisting prop erties as its dominant characteristic, said drill rod being formed and tempered to have anti-fatigue properties as its dominant characteristic, said intermediate member being formed and tempered to have shock absorbing properties as its dominant characteristic.

2. A drill adapted to be percussively driven into rock and the like, comprising a bit formed to have wear-resisting properties as its dominant characteristic, a drill rod formed to have anti-fatigue properties as-its dominant characteristic,and an intermediate member formed to have shock absorbing the same time and be of a very complex nature,-and require a capacity of absorption of the parts of the drill to be readily disassembled .f or purposes of resharpening or re-' claim as new and.desire to secure by Letters nant characteristic; said bit and rod formed to be separable from each .other.

fl. A drill adapted to be percussively driven into-rock and the like, including a detachable bit and a cylindrical interme-v diate member formed of material having shock-absorbing properties as its dominant characteristic; said intermediate member being internally threaded to provide a coupling whereby the detachable bit is secured in place.

5. A drill adapted to be perenssively driven into rock and the like, including a detachable bit and a'iiylindrical intermediate member formed of material having shock-absorbing properties as its dominant character stic; said intermediate mem f.

her being formed of chrome-nickel steel and threaded internally to provide a coupling whereby the detachable bit is secured in place.

6. A drill= adapted to be percussively driven into rock and the like, including a detachable bit and a cylindrical intermediate member formed of material having shock-absorbing properties as its dominant characteristic; said intermediate mem-. her being. internall threaded to provide a coupling for the vided exteriorly with a plurality of ribs.

7. A drill constructed of separable parts adapted to be percussively driven into rock and the like, comprising a drill-rod having anti-fatigue properties steel, an intermediate member having shock absorbing properties greater than wrought.

iron, and a bit having wear-resisting prop: erties greater than tool steel.

8. A drill construetedof adapted tobe percussively driven into rock and the like, comprising a drill rod ofalloy steel having anti-fatigue properties greater than mild steel, an intermediate member of alloy steel different from the first alloy steel, having shock-absorbing properties greater than wrought iron, and a bit of allo steel different from the other alloy steels aving Wear-resisting properties greater than tool steel.

adapted to be percussively driven into rock and the like, comprising a drill rod of vanadium steel having anti-fatigue properties as its dominant characteristic, an inter mediate member of chrome nickel steel hav ing shock-absorbing properties as its dominant characteristic, and a bit of chromeseparable. parts etachable bit, and pro- I greater than mild 9. A drillconstructed of separable parts 7 vanadium; steel having wear-resisting properties as .1ts domlnant characterist c,

10. A drill constructed of separable parts adapted tobe percussively driven into rock and the like, comprising a drill rod of vanadium steel tempered to have anti-fatigue properties as'its dominant characteristic, an

intermediate member having shock-absorb ingpropertics as its dominant characteristic, and a bit having wear-resisting properties as itsdominant characteristic.

11. A drill constructedof separable parts adapted to be percnssively driven into rock and the like, comprisingadrill rod having anti-fatigue properties as its dominant characterist-ic, an intermediate member having shock-absorbing properties as its dominant characteristic, and a bit ofchroine-vanadium steel tempered to have wear-resisting prop erties as its'domin'ant characteristic..

12.- A drill adapted to, be percussively driven into rock and the like, comp-rising separable drillin Far intermediate portion inmembers having threaded ends and a tubu ternally threaded and adapted to engage as its dominant characteristic.

witl1 said'ends, said tubular intermediate portion having shock-absorbingproperties- I 13 A drill adapted to be 'percussive'ly' driven into rock and the like, comprising a V separable bit'and'drill ro'd, including a cou formed and" pling member; said bit being tempered to have wear-resisting properties as its dominant characteristic, said drill rod being formed and temperedto have antifatigue properties as'its dominant characteristic, said coupling member being formed and tempered to have shock-absorbing prop erties as its dominant characteristic.

14. A .drill adapted to be percussively driven intorock and the like, comprising" separable drill members having threaded ends and a tubular coupling portion inter- I nally. threaded and adapted to engage with said ends, said tubular coupling .portion having shock-absorbing properties as its d0mi- 'nant characteristic.

In testimony whereof I afiix' my signatnre;

FR D W. THURS-TON. 

